First time TBI tuner

[DOCBAWRENCHTURNER]

Just looked at a 5.0L bin but not yours. Post up your bin and the data log so we can help!

But base timing says 0 and it should be about 19 at idle.

Timing is set with bypass wire (a single wire with disconnect plug, not sure where it is on your truck) disconnected and set to 0. SO if your getting 23? Something is wrong? Idle timing could be that high with wire NOT disconnected... You sure the timing light was on number 1 cylinder?

The big swing in BLM could be the 5.0L chip and 5.7L engine.

I was a GM tech for nearly six years and have set the timing on more than one vehicle, however it seems the base timing should, with the esc wire unplugged, read zero on live data, it doesn't. I'll get a formal datalog posted when I get to WiFi again. I still haven't ordered my BURN2 as I am trying to make sure my first marriage anniversary (today) has sufficient funds first, so can't upload my BIN yet. I'm positive that the timin light was on the number one cylinder. Gotta be something strange going on here. Also I had an idea, the truck dies while idling at or below 5-7 of timing. Also the throttle responce is sluggish to say the least. Is it possible that I just need to reset the IAC, that it isn't open enough and retarding the timing is causing it to flood out? Or maybe that my underlying cause is an overly rich condition that the computer is covering up by advancing the timing?


edited due to lack of punctuation and many fat fingered misspellings. (Don't you just love typing on a phone?)

[dumb_dog]

I'd like a copy of that bin when you get one!!! It's a 5.0L Manual...

Even if it were a 5.7L chip, along with 65 lb/hr cop car injectors... it would still not run well with Vortec heads = needs more spark let alone fueling adjustments.

Is the cam stock Vortec?

Mark I have a BJXP bin that came in an eBay PCM buy and it was labelled by the seller 5.0 4L60e 16197427 if you still need a copy how do I upload it. It does appear to be auto bin though from a 94 as the pwm stuff for the 95 models are not enabled. If you want it let me know how to upload it.

Also Docba my vortec 5.0 needs 10° of advance to idle well too. I can adjust the idle stop and the timing to get 0° and 650 rpm but it runs like it wants to die. When I plug in the timing set plug timing jumps to 21° advance and smooths right out. I have read that vortec head need more timing than standard heads appears to be true but I am still learning to play with this stuff. My first conversion and add to it slight engine mods so not sure what stock looks like.

[EagleMark]

Sure! Even Cal Data says it's a 5.0L Man... but it has been wrong before.

When you click Reply to thread, underneath you'll see Go Advanced, then under that box is the Attachment manager to attach files.

[Fast355]

Just looked at a 5.0L bin but not yours. Post up your bin and the data log so we can help!

But base timing says 0 and it should be about 19 at idle.

Timing is set with bypass wire (a single wire with disconnect plug, not sure where it is on your truck) disconnected and set to 0. SO if your getting 23? Something is wrong? Idle timing could be that high with wire NOT disconnected... You sure the timing light was on number 1 cylinder?

The big swing in BLM could be the 5.0L chip and 5.7L engine.

My experience with setting the timing on Vortec head motors is they will not run at all below about 10* even at idle. I give my Express 12* of cranking timing even and set the base timing at 10*BTDC at the distributor. Then account for the distributor timing in the calibration. Also I tend to start with the Hypertech 93 octane 1998 Vortec 350 timing map I have. I can post a copy of it soon if anyone needs it.

[dumb_dog]

This is the bin (BJXP) that I am using for my conversion with PCM 16197427 $OD. Also will be controlling '95 4L60e trans. Engine data: 5.0, 30 over flat top pistons, 9.5:1 compression, com cam XE262H-10, 1.52:1 roller tip rockers, Edelbrock Performer intake, vortec heads milled for 58cc combustion chambers. Do you think this bin is a good starting point, if not any recommendations??? Note I read this bin directly from the stock prom and verified they matched.

[EagleMark]

My experience with setting the timing on Vortec head motors is they will not run at all below about 10* even at idle. I give my Express 12* of cranking timing even and set the base timing at 10*BTDC at the distributor. Then account for the distributor timing in the calibration. Also I tend to start with the Hypertech 93 octane 1998 Vortec 350 timing map I have. I can post a copy of it soon if anyone needs it.

Yes if this is Vortec head, I must have thought these were both TBI head, this thread is about 2 vehicles now... I think? But I usually do the timing all in tables and leave distributor alone. Moving timing at distributor also moves injector timing, which is usually not a help until big cams are an issue.

Yeah I'd like to see the 93 octane Vortec head table!

[dumb_dog]

I didn't mean to hi-jack the thread but you are right two vehicles with similar issues base timing on vortec heads topped with TBIs. GM TBI computers expects 0° base timing and the spark tables control from there. For some reason it's very hard to get a vortec head engine to idle at 0°. I agree with fast355, DOCBA may need to start with 10° of timing at the distributer and set the initial timing scalar in the bin to match his distributer setting. Also if his bin is for a 5.0 (BJXP) and his actual engine is 5.7L his timing and ve tables will need some love or he should switch to different bin like BJYL as a starting point for his 5.7L engine.

[Fast355]

Yes if this is Vortec head, I must have thought these were both TBI head, this thread is about 2 vehicles now... I think? But I usually do the timing all in tables and leave distributor alone. Moving timing at distributor also moves injector timing, which is usually not a help until big cams are an issue.

Yeah I'd like to see the 93 octane Vortec head table!

I never liked using TDC with Vortec heads because my engine practically refused to start cold. It would windmill, almost flood itself out, and start very weakly. With timing it would fire right up.

I will have to dig up those tables, they are on my tuning laptop not my desktop.

[buddrow]

Welcome DOCBA! You have come to the right place for advice. Fast355 and Eaglemark are great guys and very knowledgable. I do agree with the concensus that u need more base timing. Havent fiddled with much vortec injection tuning but do have some exp with carbed versions and they always run better with more base timing. Just my 2 cents. Happy anniversary btw

[EagleMark]

I never liked using TDC with Vortec heads because my engine practically refused to start cold. It would windmill, almost flood itself out, and start very weakly. With timing it would fire right up.

I will have to dig up those tables, they are on my tuning laptop not my desktop.

Oh so cold start, like when timing is in By Pass... I think you may have just fixed a cold start issue I'm having on one that was perfect all summer!

[Fast355]

Oh so cold start, like when timing is in By Pass... I think you may have just fixed a cold start issue I'm having on one that was perfect all summer!

That is exactly when the issue shows up. When the temperature gets into the 30s and below. I altered the crank timing in my 0411 PCM as well. Really helped the cammed 5.7 Vortec startup as well.

One other place the advanced distributor timing helps is should the ECM ever fall into Limp Home mode. You have a better chance of actually being able to make it off the road with a little timing.

[brian617]

Mark I know you aren't a fan of advancing the distributor for base timing because of injector timing advance. One day I was just going through every single parameter in my OE XDF and ran across this... Under "BPW Limits" is "Degrees of Delay from DRP to Injector Firing" wouldn't this parameter be able to offset the injector advance?

[Roadknee]

This is the bin (BJXP) that I am using for my conversion with PCM 16197427 $OD. Also will be controlling '95 4L60e trans. Engine data: 5.0, 30 over flat top pistons, 9.5:1 compression, com cam XE262H-10, 1.52:1 roller tip rockers, Edelbrock Performer intake, vortec heads milled for 58cc combustion chambers. Do you think this bin is a good starting point, if not any recommendations??? Note I read this bin directly from the stock prom and verified they matched.

I think it's a good starting point. Set the constants correctly like cylinder volume, injector size, etc., and turn off things you're not using such as EGR. That's a pretty big cam for a 305 TBI. I think you'll be able to get it to work well, but it may be tricky to get a good idle. I'd bump the commanded idle to 800 in park and 750 in drive. The spark and fuel maps will need quite a bit of work everywhere.

I've recently been tuning the L05 and 4l60E in my 1995 K1500. That pcm with $0D mask is awesome. You'll really like what you can do with the 4L60E!

[EagleMark]

Mark I know you aren't a fan of advancing the distributor for base timing because of injector timing advance. One day I was just going through every single parameter in my OE XDF and ran across this... Under "BPW Limits" is "Degrees of Delay from DRP to Injector Firing" wouldn't this parameter be able to offset the injector advance?

[Fast355]

I think it's a good starting point. Set the constants correctly like cylinder volume, injector size, etc., and turn off things you're not using such as EGR. That's a pretty big cam for a 305 TBI. I think you'll be able to get it to work well, but it may be tricky to get a good idle. I'd bump the commanded idle to 800 in park and 750 in drive. The spark and fuel maps will need quite a bit of work everywhere.

I've recently been tuning the L05 and 4l60E in my 1995 K1500. That pcm with $0D mask is awesome. You'll really like what you can do with the 4L60E!

I have run the 305 in my Vette with TBI before when it was in the old C10. It has a Crane 272 H10 cam in it. While it did have lower than stock vacuum at about 700 rpm the vacuum signal was very stable for a 110° lsa cam it worked very well.